Blackboard drafting implements



April 23, 1968 E. E. LOWERY 3,378,927

BLACKBOARD DRAFT I NG IMPLEMENTS 4 Filed April 21, 1967 774 77 INVENTOR.

4 7 roe/v.5 vs.

United States Patent 0 3,378,927 BLACKBOARD DRAFTING IMPLEMENTS Earnest E. Lowery, 5335 Euena Vista Ave., Fair Oaks, Calif. 95628 Filed Apr. 21, 1967, Ser. No. 632,694 8 Claims. (Cl. 33--26) ABSTRACT OF THE DISCLOSURE Blackboard accessories comprising an elongated arm provided with means spaced axially thereof to releasibly receive and connect one or more pieces of chalk thereon, and means fixedly secured to one end of the arm to releasibly connect the arm on the blackboard for movement across its writing surface to selectively chalk-inscribe linear or arcuate lines thereon, and wherein adjacent pairs of linear lines may be simultaneously drawn parallel to one another and adjacent pairs of arcuate lines may be inscribed in concentric relation relative to one another.

BACKGROUND OF THE INVENTION This invention relates to the general field of drafting implements and, more specifically, the present invention pertains to implements or accessories for a conventional blackboard which enable the user thereof to inscribe, selectively, one or more linear or arcuate lines on the writing surface of the blackboard. Drafting implements of a related nature are known to be old in the art, but most of these are complex in construction and assembly necessitating high manufacturing costs, are cumbersome in use, and are difficult to maintain. As a consequence, the prior art is replete with examples of drafting implements especially designed for use in conjunction with a blackboard and which have become discarded as being of little practical use regardless of their initial cost.

Accordingly, one of the primary objects of this invention is to provide accessories or implements for use with a blackboard which obviate the above referred to disadvantages of the prior art devices. To this end it is among the foremost objects of this invention to provide an implement for a blackboard which comprises, essentially, an arm or bar having means thereon for releasibly connecting a plurality of chalk pieces in spaced relation relative to one another, and to provide as a component of the implement, means for supporting the arm for movement relative to the writing surface of a blackboard with one or more of the pieces of chalk disposed in a preselected or predetermined position relative to the arm and in chalk-inscribing engagement with the aforementioned writing surface of the blackboard.

As another object of this invention, it is proposed to provide in the support means referred to supra, means for tracking a track or rail disposed adjacent the blackboard as the arm is moved to cause each piece of chalk mounted on the arm to trace a linear line parallel to the track or rail, and to simultaneously trace a plurality of linear lines which are parallel with respect to one another.

A further object of this invention is to provide in the aforementioned support means, means for releasibly and pivotally connecting one end of the arm on the writing surface of the blackboard to permit the free end thereof to freely swing about the pivot center and to cause each chalk piece to inscribe an arcuate line with each adjacent pair of lines being concentric relative to one another.

Still another object of this invention. is to provide accessories or implements of the type generally described above wherein the implements each comprise an elongated arm and wherein the releasible chalk connecting means is axially spaced relative thereto.

Inasmuch as most conventional blackboards are today provided with an upper trim rail or flange as well as a lower chalk and eraser retaining trough, it is among the further objects of this invention to provide in one embodiment of this invention support means for tracking the rail, flange or trough and to which the arm is rigidly conected during the drawing of straight linear lines on the blackboard; and in a second embodiment of the invention to provide a vacuum means for releasibly and pivotally connecting one end of the arm on the blackboard leaving the other end free to swing about its pivotal connection in the scribing of arcuate lines thereon.

It is a still further object of this invention to provide blackboard accessories or implements of the type to which reference has been made above, wherein the arms include a flexible resilient element enabling them to be temporarily twisted, canted or deformed to turn the blackboard engaging ends of the chalk pieces at an angle relative to the blackboard Writing surface whereby fine chalk lines may be drawn.

This invention contemplates, as a still further object thereof, the provision of blackboard drafting implements as described above, wherein the implements are noncomplex in construction and assembly, inexpensive to manufacture and maintain, and which are rugged and durable in use.

Other and further objects and advantages of the instant invention will become more manifest from a consideration of the following specification when read in conjunction with the annexed drawing.

SPECIFICATION In the drawing:

FIGURE 1 is a front elevational view illustrating one embodiment of a blackboard drafting implement constructed according to this invention, and wherein one end of the chalk carrying arm is shown as being carriage connected to the upper track or rail end of a conventional blackboard for tracking movement thereon;

FIGURE 2 is a side elevational view of the embodiment of the invention shown in FIGURE 1;

FIGURE 3 is a fragmentary exploded perspective View showing the component elements of the arm;

FIGURE 4 is an enlarged detail cross-sectional view, FIGURE 4 being taken substantially on the horizontal plane of line 4-4 of FIGURE 1, looking in the direction of the arrows;

FIGURE 5 is the front elevational view of a second embodiment of a blackboard drafting implement constructed according to this invention, this figure showing one end of the chalk carrying arm releasibly and pivotally connected on the writing surface of a blackboard;

FIGURE 6 is a side elevational view of the implement shown in FIGURE 5; and

FIGURE 7 is an enlarged fragmentary detail crosssectional view, FIGURE 7 being taken substantially on the vertical plane of line 7-7 of FIGURE 5, looking in the direction of the arrows.

Referring now more specifically to the drawing, reference numeral 10 designates, in general, a blackboard drafting implement constructed in accordane with the teachings of one embodiment of this invention. As is illustrated in FIGURES 1 to 4, inclusive, the implement is seen to comprise an elongated substantially rectangular compound arm or bar 12 which includes a pair of external elongated substantially rectangular identically constructed cover plates 14, 16, preferably but not necessarily formed of a light weight material such as aluminum, for example. The opposed ends of each plate 14 16 are rounded as at 18, 20, and each plate is cut or stamped to provide a series of transversely extending axially spaced alternating rivet receiving openings 22 and larger chalk receiving openings 24. The distance between the center lines of the openings 22, 24 of each plate 14, 16 in each instance correspond with one another whereby the openings 22 and 24 on one plate confront and are coaxially aligned with the corresponding openings in the other plate when the plates 14, 16 are juxtaposed relative to one another.

Interposed between the plates 14, 16 is an elongated substantially rectangular flexible elastic liner 26 having a rounded end 28 and, preferably an opposed squared end 30 (see FIGURE 2). The width of the liner 26 substantially equals the respective widths of the plates 14, 16, but the axial length of the liner 26 is somewhat less than the axial length of the plates 14, 16 to serve a purpose to be described; and the liner 26 is formed with a plurality of pairs of transversely extending slits 3t intersectiong at points 32 intermediate their respective ends to form a plurality of tabs 33 (see FIGURES l and 4) therebetween. The spacing between each adjacent pair of points of intersection 32 is equal to center line distance between each adjacent pair of openings 24.

The arm or bar 12 is assembled by superimposing the plates 14, 16 against, respectively, the remotely disposed sides of the liner 26 with the rounded ends 20, 28 thereof being flush with one another. The rivet openings 22 and chalk receiving openings 24 of the plates 14, 16, respectively, now become coaxially aligned with one another, and the points of intersection 22 of the slits 30 will fall on the center lines of the immediately adjacent confronting pairs of aligned openings 24. Rivets 34 are now passed through the pairs of aligned openings 22 formed in the confronting plates 14, 16, and the rivets are secured in the conventional manner to unitize the compound arm or bar 12.

Inserted between the plates 14, 16 adjacent their other ends 18 is one end of an elongated substantially rectangular tongue 35 formed of a strip of flexible plastic material. This end of the tongue 35 normally abuts the end 30 of the liner 26 and is fixedly connected between the plates 14, 16 as by rivets 36. The other end of the tongue 35 projects longitudinally from between the plates 14, 16 beyond the ends 18 thereof to serve a function to be described.

A carriage 38 (see FIGURES 1 and 2) is provided for v the arm 12, the carriage 33 being relatively noncomplex in construction comprising as it does, a substantially triangular block 40 formed of any suitable material. Adjacent each end of the base 42 of the block 40 is a wheel 44 journalled for rotation on one end, respectively, of a pair of shafts 46, the other ends of the shafts 46 extend transversely through the block 40 and being secured thereon by conventional means here designated by a reference numeral 48. With reference to FIGURES l and 2 of the drawing, it is here important to note that the diameter of each wheel 44 is such that a portion of its circumferential periphery 50 constantly projects above the plane of the base 42, all to serve a purpose and function to be described infra.

The apex end 52 of the block 40 is inverted with respect to its base end 42, and this end 52 of the block 40 is provided with a transverse vertically elongated slot 54, the longitudinal axis of the elongated slot 54 being substantially coincident with the altitude of the block 40. This slot 54 slidably receives one end of the shaft 56 therethrough, this end of the shaft 56 being held in adjusted position relative to the slot 54 as by conventional means 58. The other end of the shaft 56 rotatably supports a third wheel 60.

As is seen in FIGURES 1 and 2 of the drawing, the aforementioned other end of the tongue 34 is superimposed against that side of the block 40 remote from the wheels 44, 60 and adjacent the apex end 52 to which it is fixedly and rigidly connected as by rivets 62,. The connection is such as to position this end of the tongue 34 in close proximity to the adjacent end of the slot 54.

At 64 is designated a conventional blackboard having a surface 66 on which chalk marks may be inscribed. The blackboard 64 is of conventional construction and as such is generally rectangular in configuration to thus provide opposed top and bottom ends 68, 76, respectively, which normally extend parallel to one another. In the usual manner, the upper end 68 of the blackboard 64 is shown in FIGURES 1 and 2 as being provided with a trim piece or rail 72 fixedly secured thereon and which projects laterally away from the writing surface 66. As is normal and conventional practice, the blackboard 64 as shown in the last mentioned figures is also provided with a longitudinal extending chalk and eraser trough 74 which is fixedly connected by conventional means to the lower end 70 of the blackboard 64 and projects laterally away from the writing surface 66 thereof in the same direction as the rail 72. The rail 72 and trough 74 confront one another in vertically spaced and substantially parallel relationship with respect to each other.

In the embodiment of the invention as it is shown in FIGURES 1 to 4, inclusive, the arm 12 is adapted to be carried on the carriage 38 laterally across the blackboard 64 with the arm 12 in laterally spaced and confronting relationship relative to the surface 66 thereof. To this end, the shaft 56 is adjusted, vertically, relative to the shafts 46 in such a manner that the Wheels 44 make tangential engagement with the upper side of the rail 72 and the wheel 60 makes tangential engagement with the underside thereof. Thereafter, the fastening means 58 is actuated to secure the wheel 60 in this adjusted relationship relative to the Wheels 44. The arm 12, thus, subtends from the carriage 38 and remains supported therefrom as the arm 12, and consequently, the carriage 42 is shifted by the operator towards one or the other of the ends of the rail 72.

Referring now more specifically to FIGURES 2 and 4 of the drawing, selected ones of the pairs of aligned and confronting openings 24 formed in the plates 14, 16 are adapted to receive therethrough pieces of chalk such as the piece indicated in FIGURE 4 by reference numeral 76. As the chalk 76 is passed through the openings 24 of the plates 14, 16 it is necessarily forced through the slits 30 substantially at their point of intersection 32. As the chalk 76 passes through the aligned openings 24 in the direction of the writing surface 66 of the blackboard 64, the tabs 33 are displaced in the same direction to extend outwardly and beyond the plate 16 and to releasibly embrace and secure adjacent portions of the chalk piece 76 therebetween.

In the use of the implement 16 as described above and illustrated in FIGURES 1 to 4, inclusive, of the drawing, and assuming that the carriage 38 has been mounted on the rail 72, the operator will insert one or more pieces of chalk 76 through the openings 24 formed in the plates 14, 16 to the extent that the scribing ends 77 thereof engage against the writing surface 66 of the blackboard 64. It will be understood, of course, that the pieces of chalk 76 may be axially adjusted relative to the arm 12 from time to time to adjust the same for Wear. With the pieces of chalk 76 so mounted in the arm 12, as the arm 12 is moved transversely across the writing surface 66 the carriage 38 will track the rail 72 and each piece of chalk 76 will scribe a line on the surface 66 parallel to the planar travel of wheels 44, 66* as they track the rail '72. Such scribed lines will not only be parallel to the rail 72 but will also be parallel to one another and, in the arrangement shown, will be vertically spaced relative to each other.

When it is desired to remove the implement 10 from the board 60 it is only necessary that the carriage 38 be pulled laterally away from the rail 72 to effect disengagement of the wheels 44, 60 therefrom. To reinstall the implement 10 it is only necessary for the user to slide the wheels 44, 60 transversely across the projecting end of the rail 70 in the reverse direction. Once the wheel 60 has been aflixed in suggested relationship relative to the 72 no further adjustment thereof is required relative to the wheels 44 as the operator, in his further use of the implement removes the carriage 38 from the rail 72 and/or remounts the same thereon.

The triad arrangement of the wheels 44, 60 insures the stability of the movement of the carriage 38 longitudinally of the rail 72 and, of course, the chalk lines scribed on the surface 66 by the chalk pieces 76 will retain their parallelism regardless of whether or not the longitudinal center line of the arm 12 is coincident with the altitude of the carriage 38.

As has been mentioned above, the tongue 35 is preferably formed of a flexible plastic material which will permit, to some degree, a twisting of the arm 12 about its longitudinal axis. This twisting or canting of the arm 12 relative to the surface 66 enables the operator to present relatively sharp chalk edges 77A or 77B to the writing surface 66 to draw relatively fine chalk lines when the normal surface engaging end 77 becomes blunted or flattened in its normal usage.

The implement 10 may also be used to scribe vertically spaced parallel lines on the surface 66 even in the absence of a rail or equivalent means such as is indicated by reference numeral 72. Assuming that the blackboard 64 is conventional to the extent that it is at least provided with the chalk trough or rack 74 described above which includes the substantially planar elongated trough surface 74A, the implement 10 is inverted from its position shown in FIGURES 1 and 2 of the drawing, and the wheels 44, which project as described above from beyond the plane of the base 42 are engaged against the surface 74A with the arm 12 again disposed and laterally spaced in confronting relationship relative to the writing surface 66, and parallel chalk lines are drawn as the rollers 44 longitudinally track the surface 74A.

In FIGURES 5 to 7, inclusive, a second embodiment of this invention is shown. In these figures, reference numeral 80 designates the implement, in general, and again it is seen that the implement 80 comprises an elongated substantially rectangular arm or bar 12' constructed sub stantially identically with respect to the arm or bar 12 described in the preceding embodiment. Thus, and for convenience of identification, those elements of the bar 12' finding their counterparts in the arm 12 bear the same reference numerals but to which prime marks have been added to differentiate the latter from the former. In this second embodiment of the invention, the lower ends 28' of the plates 14, 16 and liner 26 are shown as being covered by a Strip of felt or sponge rubber indicated by reference numeral 82 to prevent these ends of the compound arm 12 from damaging the surface 66' of the blackboard 64 upon inadvertent or accidental engagement therewith. Any conventional means, adhesive (not shown) for example may be utilized to effect the connection between the strip 82 and the compound arm 12'. Obviously, this same element could be added, if desired, to the arm 12. 4

The tongue 35' is, in the second embodiment of the invention, provided with a lateral flange 84 immediate its ends, the outer end of the flange 84 terminating in an extension 86 offset but extending parallel to the tongue 35'. The offset extension 86 is formed with a substantially centrally located transversely extending opening 88 to which further reference wil lbe made infra.

The implement is adapted for use in conjunction with a conventional blackboard such as that indicated by reference numeral 64 (supra) and is especially designed to draw arcuate lines as contrasted against the straight lines drawn by the device 10 of FIGURES 1 to 4, inclusive. To this end, there is provided a conventional flexible suction cup 9% which may be formed of rubber or other suitable materials. The suction cup 90 is provided with a concave-convex main body portion 92 having a substantially plane area circumferential marginal edge 94, all in the usual manner. From the convex side of the main body portion 92, and substantially at the apex thereof, laterally projects an integrally formed neck 96.

Embodied within the main body portion 92 and neck 96 is an internally threaded sleeve 98 having a flanged inner end 100 to prevent the inadvertent separation of the sleeve 98 from the suction cup 90. The sleeve 98 is seen to open into the plane of the outer end of neck 96, and the sleeve 98 to releasibly receive therein the threaded inner end of a headed bolt 102. The outer end of the bolt 102 projects beyond the planar end of the neck 96, and mounted on this end of the bolt 102 and engaging against the planar end of the neck 96 is the spacer washer 104 which may be formed of metal or other suitable material. Superimposed on the washer 104 is a second washer 166 preferably formed of a plastic material, this last mentioned washer being telescoped over the projecting end of the bolt 102 and has superimposed on the outer side thereof the flange 108 of a metallic flange to bushing 110. The latter is tightly fitted within the aforementioned aperture or opening 88 formed in the extension 86.

The bushing 110 is followed, outwardly, by a washer 112 which is held clamped between the head 114 of the bolt 102 and the adjacent end of the bushing 110 in such manner that the washer 112 is axially spaced relative to the bolt 162 from the tongue extension 86.

The above described assembly is such that the component elements mounted and carried on the bolt 102 are held against axial displacement relative thereto while, at the same time, freely permitting the arm 12 and including its tongue and extension 86 to pivot freely about the bushing 110.

From the above described construction of the implement and its shown association with the blackboard 64' the use of the implement 80 is seen to be self-evident. However, to briefly describe the same it will be understood that it is only necessary for the user or operator to engage the peripheral edge 94 of the suction cup against the writing surface 66 of the blackboard 64 and to compress the same thereagainst causing the suction cup '99 to be secured thereto, all in the conventional manner. The arm 12, being freely mounted for pivotal action around the bolt 102 will normally depend therefrom in its upright position shown in FIGURES 5 and 6 of the drawing. The arm 12 may then be swung in either direction about its pivotal axis to thereby scribe one or more arcuate lines in vertically spaced relation relative to one another. Depending upon the location of the suction cup 90 on the writing surface 66' of the blackboard 64, the lines drawn by the chalk pieces 76' may be complete circles, and if two or more thereof are drawn simultaneously, the circles will be concentrically spaced from one another.

In the first embodiment of this invention, the scribed chalk lines are assigned reference numeral 200. Each line 290 will extend in a parallel relation relative to the linear path of travel of the carriage 38 and will be, of course, vertically spaced and parallel with respect to one another. The spacing between the chalk lines 200 is accomplished by the selective insertion of each piece of r chalk through a pair of preselected aligned openings 24 this invention in detail, it will be understood that the same are offered merely by way of example, and that this invention is to be limited only by the scope of the appended claims.

I claim:

1. Apparatus for scribing chalk lines on the scribing surface of a blackboard comprising:

a substantially rigid member including an elongated compound arm having a pair of confronting substantially rigid plates and a flexible liner interposed therebetween, and means connecting together said plates and liner as a unit;

said plates each having a series of axially spaced transversely extending openings formed therein with the openings of one of said plates confronting and being coaxially aligned, respectively, with one of the openings formed in the other of said plates, and said liner having transversely extending slits formed therein to provide tabs registering with each pair of coaxially aligned openings to embrace and hold a piece of chalk passed through a selected pair of said aligned openings and to hold adjacent pieces of chalk in axially spaced relationship relative to said rigid member and in scribing relation relative to said scribing surface; and

means supporting said rigid member for movement relative to said scribing surface.

2. Apparatus as defined in claim 1 and elongated flexible tongue means connecting an end of said arm with said supporting means enabling said arm to be canted relative to said scribing surface.

3. Apparatus as defined in claim 2 wherein:

said supporting means includes a wheeled carriage adapted to track rail means disposed adjacent said blackboard, and

means rigidly connecting said tongue and arm on said carriage and against movement relative thereto.

4. Apparatus as defined in claim 3 wherein:

said wheel carriage is provided with wheels engageable with opposed sides of said rail means.

5. Apparatus as defined in claim 4 wherein:

said wheeled carriage includes a substantially triangular block,

means projecting laterally from one common side of said block and at each corner thereof to journal one of said wheels for rotation thereon, the wheels at the base corners of said block having portions thereof continuously projecting beyond said base, and

said tongue being rigidly connected to the apex end of said block.

6. Apparatus as defined in claim 2 wherein:

said support means comprises a suction cup having a concave-convex main body portion, and

means swingably connecting said tongue on the convex side of said main body portion.

7. Apparatus as defined in claim 6 wherein:

said main body portion includes an elongated neck projecting laterally from the central portion of said convex side of said main body portion, and

said last named connecting means comprises shaft means.

8. Apparatus as defined in claim 7 wherein:

said tongue includes an offset extension projecting substantially parallel to said member.

References Cited UNITED STATES PATENTS 724,445 4/1903 Decker 334l 858,254 6/1907 Benedict 33-32 1,013,086 12/1911 Winters 33-26 1,244,272 10/1917 VVOlf 3327 1,571,777 2/1926 Golden 3327 1,624,280 4/1927 Rasmusen 33-26 HARRY N. HAROIAN, Primary Examiner. 

